The Pike River Mine families and the miners' union have each been awarded $12,500 in costs after a failed bid by Peter Whittall's lawyers to reopen the Royal Commission of Inquiry.

Last month, the High Court ruled that the commission did not need to be reopened to hear more evidence.

Applicants, including the mine's former chairman John Dow and former chief executive Mr Whittall, wanted evidence from three workers introduced and cross-examined.

But Justice Ron Young said the men had been informed of all the evidence before the commission of any allegations made against them, and had the opportunity to respond to that evidence in those allegations.

The families of the 29 dead men and the Engineering, Printing and Manufacturing Union both sought costs, of $18,338 and $19,275.

In a written judgement dated October 18, Justice Young agreed they should have some allowance toward their costs.

"It was appropriate that they be joined and appropriate that they made submissions with respect to the review."

Without the families and union there may not have been any party to oppose the bid to reopen the commission, as the commission itself could not advocate for its decision.

Justice Young also said the families and the union had interests in the "speedy report of the commission for such matters as public safety".

"I accept, however, that there was a limited degree of overlap between the submissions and that the intervener's involvement in the proceedings.

"In those circumstances rather than a fee calculated directly on the scale I think a lump sum award for each is appropriate."